Sullivan County, IN: the USDA septic-suitability picture

Very limited

Sullivan County, IN: USDA's soil survey calls 91.4% of the county "Very limited" for a septic leach field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 91.4% of the county. For scale: 447.196 square miles and 20,768 people call Sullivan County home.

Before you rely on this for one lot

This is a countywide, area-weighted figure across every soil survey map unit in Sullivan County, IN - never a reading for one specific parcel. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).

Budgeting for a system in Sullivan County, IN

Sullivan County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.

Sullivan County's rank among Indiana counties

Among the 3,058 rated counties on this site, Sullivan County, IN ranks 1,123 most-constrained nationally, and 56 of 90 within Indiana.

Further reading

How this rating is built, and its real limits · Conventional vs. engineered septic systems